Thanks SO Much for ALL the Data: The Amundsen Sea Sector Data Set: Applications with UMISM: Where and How Much WATER? What WILL happen in the future? James L Fastook University of Maine We thank the NSF, which has supported the development of this model over many years through several different grants. James L Fastook University of Maine We thank the NSF, which has supported the development of this model over many years through several different grants.

BEDMAP vs AGASEA/BBAS* ★ Airborne Geophysical survey of the Amundsen Sea Embayment (Holt et al., 2006 & Vaughan et al., 2006)

Embedded Models ● High-resolution, limited domain – runs inside ● Low-resolution, larger domain model. ● Modeling the whole ice sheet allows margins to be internally generated. – No need to specify flux or ice thickness along a boundary transecting an ice sheet. ● Specification of appropriate Boundary Conditions for limited-domain model, based on spatial and temporal interpolations of larger-domain model. ● High-resolution, limited domain – runs inside ● Low-resolution, larger domain model. ● Modeling the whole ice sheet allows margins to be internally generated. – No need to specify flux or ice thickness along a boundary transecting an ice sheet. ● Specification of appropriate Boundary Conditions for limited-domain model, based on spatial and temporal interpolations of larger-domain model.

Nested Grids: nodes, 40 km

Nested Grids: 9000 nodes, 10 km

Nested Grids: nodes, 5 km

Nested Grids: 6402 nodes, 5 km

Nested Grids: 9000 nodes, 10 km

Nested Grids: nodes, 5 km

Nested Grids: 6402 nodes, 5 km

Nested Grids: nodes, 5 km

Nested Grids: 6402 nodes, 5 km

Nested Grid: Summary & runtimes GridNodesDeltaXDeltaTSteps Time/step (s) Time (hr) A E F G Full (est)32.0

Vostok Temperature Proxy

Area-growth and retreat ●

Volume-growth and retreat ●

Water Peak during retreat ●

Data (Rignot 2004) and Results

Data (Lang 2004) and Results

PIG: velocity ●

PIG: bed ●

PIG: thickness ●

PIG: water ●

PIG: velocity ●

Thwaites: velocity ●

Thwaites: bed ●

Thwaites: thickness ●

Thwaites: water ●

Thwaites: velocity ●

Growth and retreat: thickness ● See AGASEA:Thick ● Requires bandwidth, movies are large… ● /AGASEA%3AThick.html /AGASEA%3AThick.html

Growth and retreat: velocity ● See AGASEA:Velo ● Requires bandwidth, movies are large… ● /AGASEA%3AVelo.html /AGASEA%3AVelo.html

Growth and retreat: water ● See AGASEA:Water ● Requires bandwidth, movies are large… ● /AGASEA%3AWater.html /AGASEA%3AWater.html

Thwaites: thickness ● See Thwaites:Thick ● Requires bandwidth, movies are large… ● /Thwaites%3AThick.html /Thwaites%3AThick.html

Thwaites: velocity ● See Thwaites:Velo ● Requires bandwidth, movies are large… ● /Thwaites%3AVelo.html /Thwaites%3AVelo.html

Thwaites: water ● See Thwaites:Water ● Requires bandwidth, movies are large… ● /Thwaites%3AWater.html /Thwaites%3AWater.html

PIG: Thickness ● See PIG:Thick ● Requires bandwidth, movies are large… ● /PIG%3AThick.html /PIG%3AThick.html

PIG: velocity ● See PIG:Velo ● Requires bandwidth, movies are large… ● /PIG%3AVelo.html /PIG%3AVelo.html

PIG: water ● See PIG:Water ● Requires bandwidth, movies are large… ● /PIG%3AWater.html /PIG%3AWater.html

Future Retreat Scenarios ● Beginning with end of glacial cycle – Run 100 years with conditions that produced present grounding line position. – Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m. ● Beginning with end of glacial cycle – Run 100 years with conditions that produced present grounding line position. – Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m.

Weertman Parameter ●

Future Retreat Scenarios ● Beginning with end of glacial cycle – Run 100 years with conditions that produced present grounding line position. – Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m. ● Two Cases: 1. Condition is applied everywhere. Ross and Filchner-Ronne, as well as East Antarctica. 2. Condition is only applied in Amundsen Sea Sector. Two distinct patterns of retreat emerge for these two cases. ● Beginning with end of glacial cycle – Run 100 years with conditions that produced present grounding line position. – Then 1900 years with 1.00 Weertman thinning at grounding line wherever the bed is below 550 m. ● Two Cases: 1. Condition is applied everywhere. Ross and Filchner-Ronne, as well as East Antarctica. 2. Condition is only applied in Amundsen Sea Sector. Two distinct patterns of retreat emerge for these two cases.

Case 1: thickness ● See Case 1:Thick ● Requires bandwidth, movies are large… ● /Case 1%3AThick.html /Case 1%3AThick.html

Case 1: velocity ● See Case 1:Velo ● Requires bandwidth, movies are large… ● /Case 1%3AVelo.html /Case 1%3AVelo.html

Case 1: water ● See Case 1:Water ● Requires bandwidth, movies are large… ● /Case 1%3AWater.html /Case 1%3AWater.html

Case 2: thickness ● See Case 2:Thick ● Requires bandwidth, movies are large… ● /Case 2%3AThick.html /Case 2%3AThick.html

Case 2: velocity ● See Case 2:Velo ● Requires bandwidth, movies are large… ● /Case 2%3AVelo.html /Case 2%3AVelo.html

Case 2: water ● See Case 2:Water ● Requires bandwidth, movies are large… ● /Case 2%3AWater.html /Case 2%3AWater.html

Future: water percent & volume ●

1. Conclusions: Past cycle From a modeler’s perspective the new data set is great. The nested, embedded model captures the salient features of the Amundsen Sea Sector velocity field. The water system is  dendritic,  follows bed topography,  appears to be decreasing in area as the present is approached,  with peak water volumes during or just prior to periods of retreat. From a modeler’s perspective the new data set is great. The nested, embedded model captures the salient features of the Amundsen Sea Sector velocity field. The water system is  dendritic,  follows bed topography,  appears to be decreasing in area as the present is approached,  with peak water volumes during or just prior to periods of retreat.

2. Conclusions: Future retreat Retreat scenarios depend strongly on whether grounding-line thinning is confined to the Amundsen Sector (Case 2) or involve the Ross and Filchner-Ronne too (Case 1). In Case 1, retreat is much faster and more extensive, and comes in from behind the Amundsen Sea Sector. Case 2 looks more like the classic “weak underbelly” with retreat in Thwaites and up the PIG with a non-smooth episodic retreat punctuated by pulses of water production that seem to precede retreat steps. Retreat scenarios depend strongly on whether grounding-line thinning is confined to the Amundsen Sector (Case 2) or involve the Ross and Filchner-Ronne too (Case 1). In Case 1, retreat is much faster and more extensive, and comes in from behind the Amundsen Sea Sector. Case 2 looks more like the classic “weak underbelly” with retreat in Thwaites and up the PIG with a non-smooth episodic retreat punctuated by pulses of water production that seem to precede retreat steps.

Case 1: Rate ● Case 1:Rate ● Requires bandwidth, movies are large… ● /Case 1%3ARate.html /Case 1%3ARate.html

Case 2: Rate ● See Case 2:Rate ● Requires bandwidth, movies are large… ● /Case 2%3ARate.html /Case 2%3ARate.html